1. Field of the Invention
The present invention relates to an improvement to a converging solar module capable of performing efficient electricity generation by converting, while tracking, sunlight.
2. Description of the Prior Art
Conventionally, a solar battery has been utilized for various purposes, and use of such a solar battery in generating relatively high power electricity has also been considered. In constituting such a large-power generating system utilizing a solar battery, the solar battery is required to generate an increased amount of electricity, and it is therefore necessary to increase an amount of light coming into the solar cell. As means for increasing the amount of incoming light, a converging solar module has been proposed. With this module, since sunlight is converged through a lens, an increased amount of light is introduced. As a result, a usage area of an expensive solar battery can be reduced, as well as reducing the costs of the module.
More particularly, in a converging solar module, sunlight is converged so as to be 10 to 1000 times more intense before irradiating a solar cell. Thus, only an area of the solar cell that is reduced to 1/10 to 1/1000 in size is needed to receive the same amount of sunlight, which contributes to a considerable reduction of costs. In this case, however, such a module requires a larger converging lens, not to mention a larger pedestal for holding the lens.
Provided that the sun always stays at the same position, as shown in FIG. 24, the sunlight 12 is converged through a converging lens 10 to form a converged spot at a constant point, that is, at the focal point of the lens 11 or the vicinity thereof, i.e., a small area including the focal point. Thus, with a solar cell 16 placed where the converged spot 14 is formed, effective electricity generation can be performed.
In reality, however, as the sun moves over a period of time, the incoming direction of the sunlight 14 to the converging lens 10 varies with time. This may cause the converged spot 14 to be formed off the solar cell 16 with some incoming angles, as shown in FIG. 25, resulting in a considerably reduced amount of electricity being generated by the solar cell 16.
Therefore, in order to secure a sufficient amount of sunlight irradiating the solar cell 16, it is necessary for the converging lens 10 and the solar cell 16 to always be facing in the direction from which the sunlight is coming.
Japanese Utility Model laid-Open Publication No. Sho 62-5315 discloses such a solar module, in which, as shown in FIG. 26, the converging lens 10 and the solar cell 16 are controlled so as to always face the sun by means of a tracking mechanism (not shown). With this arrangement, the converged spot 13 always falls within the solar cell 16, so that favorable generation of electricity is achieved all the time.
In the module of FIG. 26, however, since it is necessary to move both the converging lens 10 and the solar cell 16, and thus the pedestal holding them, a large mechanism is required to move such large components, including a converging lens 10 which generally has a large size and thus a heavyweight. This inevitably adversely affects the costs. Moreover, since such a large tracking mechanism is driven with a large force, the generated electricity is partly consumed for driving the mechanism. This resultantly deteriorates the generation efficiency of the whole system.
Further, when the temperature of the solar cell 16 has risen due to converged sunlight, the solar cell 16 needs to be cooled down, or else the performance of electricity generation will be deteriorated. Therefore, a cooling mechanism is necessary in addition to the aforementioned tracking mechanism, which results in a complicated structure of the overall system.